1. Evidence Based Medicine
Doing what is right

2. Definition
 Conscientious, explicit, judicious use of
current best evidence in making
decisions about care of an individual
patient
 Involves integrating individual clinical
experience with best external evidence
from systematic research

3. Types of EBM
 Evidence based guidelines- production
of guidelines, policy and regulations to be
used at the organizational or institutional level
 Evidence based individual decision
making- use of available evidence to provide
best treatment to an individual patient, by an
individual physician

4. Answering clinical question
 Formulate a question
 Search the literature
 Evaluate the literature
 Apply available evidence in management

5. Stratifying evidence
 Prospective, randomised, double-blind placebo
controlled trial
 Prospective, randomised double-blind comparative
trial
 Systematic review- Meta-analysis
 Prospective controlled trial, without randomisation
 Sub-group analysis or Retrospective study
 Uncontrolled trials- Cohort/Case-control studies
 Case series or case reports
 Expert opinion

6. Levels of evidence
 I- from at least one RCT
 II- from controlled trials without
randomization, multicentric case-control
or cohort studies or uncontrolled trials
 III- opinions of respected authorities,
based on clinical experience or reports
of expert committees

7. Categories of
recommendation
 A- good scientific evidence that
benefits >>> potential risks
 B- fair scientific evidence that
benefits >> potential risks
 C- fair scientific evidence that
benefits > potential risks
 D- fair scientific evidence that
risks > benefits
 I- insufficient scientific evidence

8. Clinical trial
 Study done to allow safety and efficacy
data to be collected for health
interventions
 Needs a protocol
 Investigators recruit patients, administer
treatment, collect data over specified
time period
 Data is analysed using statistical tests

9. Types of Clinical trials
 Prevention trial
 Screening trial
 Diagnostic trial
 Treatment trial
 Quality of life trial
 Compassionate use trial

10. Terms
 Randomised- subjects are randomly
assigned
 Double-blind- subjects and researchers do
not know the treatment being given, to
prevent any bias
 Placebo controlled- use of placebo helps
isolate the effect of study treatment

11. Phases of Clinical trials
 Pre-clinical studies- in-vitro or animal
studies to obtain preliminary efficacy,
toxicity and pharmacokinetic data
 Phase 0- subtherapeutic doses to few
patients to get pharmacokinetic and
pharmacodynamic data

12. Phases- contd.
 Phase I- assesses safety, tolerability and
dose range in healthy volunteers
 Phase II- assesses dose and efficacy in a
larger group of volunteers and patients
 Phase III- randomised controlled
multicenter trials on large patient group for
effectiveness of the treatment
 Phase IV- post-marketing safety surveillance

13. Statistical terms
 p-value- <0.05 considered significant
 Relative risk- risk of an event relative to
exposure
 Hazard ratio- ratio between the predicted
hazard for members of two groups
 Odds ratio- ratio of the odds of an event
occurring in one group to the odds of it
occurring in another group

14. Statistical terms- contd.
 SeNsitivity- probability of a positive test
result in someone with target disease
i.e. true Positive
 SPecificity- probability of a negative test
result in someone without the disease
i.e. true Negative

15. Statistical terms- contd.
 Number needed to treat (NNT)-
number of patients needed to treat to
prevent one clinical event
NNT= 1/absolute risk reduction
 Number needed to harm (NNH)-
for harmful effects of the treatment

16. Quality of Clinical trials
 Clearly defined eligibility criteria and have
minimal missing data
 Results must be generalizable in clinical
practice
 Adequate follow-up for defined outcomes to
occur and to detect differences between arms
of study
 Sufficient number of patients to detect a
significant difference

17. Limitations
 Ethical issue of offering or not, of an unproven
treatment
 Cost of trial and consequent source of funding
 Generalizability, comparability and extrapolation of
results
 Publication bias
 Use for rationing resources by economists,
policymakers and managers
 Availability of credible evidence
 Applying statistics to individuals